Search results for "I.2"

A Collection of Chemical Reaction Engineering Solutions in Photocatalysis

2017

There are problems in photocatalysis that researchers cannot disregard in a rigorous study of photocatalytic systems. The purpose of the present work is to show how chemical reaction engineering can answers to the previous questions, thus helping scientists to face researches on photocatalysis more successfull and consistenty

Photocatalytic conversion of glucose in aqueous suspensions of heteropolyacid-TiO2 composites.

2015

Photocatalytic conversion of glucose was carried out in aqueous suspensions in the presence of dfifferent commercial and home prepared TiO2 samples functionalized with a commercial heteropolyacid. Different reaction extents and distribution of intermediate oxidation products were observed depending on the photocatalyst.

TiO2 Nanocristalline samples used to photo-oxidize aromatic alcohols to aldehydes

2010

Photocatalytic synthesis of piperonal in aqueous TiO2 suspensions

2013

Synergistic effect between hydrodynamic conditions during Ti anodization and acidic treatment on the photoelectric properties of TiO2 nanotubes

2015

In the present work, the combined influence of controlled hydrodynamic conditions during Ti anodization and the acidic treatment with HClO4 on the photoelectric properties of mixed anatase/rutile TiO2 nanotubes has been studied. Anodized samples were analyzed by means of Field Emission Scanning Electronic Microscopy (FE-SEM), Confocal Raman Microscopy, electrochemical measurements (electrochemical impedance spectroscopy and Mott-Schottky analysis) and photoelectrochemical measurements. It has been observed that the use of hydrodynamic conditions increases the surface area of nanotubes, while acidic treatment enhances their conductivity. Besides, there is a clear synergistic effect between t…

Photoelectrocatalytic oxidation of 3-pyridinemethanol to 3-pyridinemethanal and vitamin B3 by TiO2 nanotubes

2020

In this paper, the first photoelectrocatalytic (PEC) 3-pyridinemethanol oxidation to 3-pyridinemethanal and vitamin B-3 was investigated. To meet this aim, efficient nanotube structured TiO2 on a Ti plate as a photoanode was prepared by an anodic oxidation method in ethylene glycol and characterized by XRD, SEM, and photocurrent techniques. The effect of nanotube morphology, applied potential, Na2SO4 concentration, stirring speed of solution, and pH on the reaction activity and product selectivities were investigated. The TiO2 phase of all of the anodes was mainly the anatase one. The PEC activity, the intensity of the XRD peak and the photocurrent increased by increasing the nanotube lengt…

Photoelectrochemical Evidence of Cu2O/TiO2 Nanotubes Hetero-Junctions formation and their Physicochemical Characterization

2014

Cu2O/TiO2 nanotubes heterojunctions were fabricated by electrochemical deposition of cuprous oxide on TiO2 nanotubes arrays grown by anodizing. X-ray diffraction and Raman Spectroscopy analysis allows for identification of Cu2O, whose morphological features were studied by Scanning Electron Microscopy as a function of the charge circulated during the electrodeposition step. Photoelectrochemical measurements in aqueous solutions evidenced a red shift of the light absorption threshold of TiO2 nanotubes due to the presence of cuprous oxide even for very low circulated charges, while electrochemical impedance measurements proved a significant reduction of the electrode impedance due the presenc…

Plasmonic versus catalytic effect of gold nanoparticles on mesoporous TiO2 electrodes for water splitting

2014

a b s t r a c t Solar water splitting with metal oxide semiconductors constitutes a promising approach to the conversion of solar energy into chemical energy stored in the atomic bonds of hydrogen molecules. In the present study, we evaluate the effect of the presence of Au nanoparticles on the photoelectrochemical behaviour of mesoporous TiO2 to photo-oxidize water. We observe that the presence of Au nanoparticles leads to enhanced photocurrents for water oxidation and we explore the origin of this enhancement by optical and electrochemical characterization techniques. Our results indicate that although the Au nanoparticles are responsible for a localized surface plasmonic resonance effect…

Diffusive equilibrium properties of O2 in amorphous SiO2 nanoparticles probed via dependence of concentration on size and pressure

2014

An experimental study on the diffusive equilibrium value of interstitial O2 in silica nanoparticles was carried out on samples with average particles diameter 40, 14, and 7 nm. The investigation was performed by measuring the concentration of interstitial O2 by Raman and photoluminescence techniques. The dependence of diffusive equilibrium concentration on pressure and temperature was investigated in the pressure range from 0.2 to 76 bar and in the temperature range from 98 to 244 °C. The equilibrium concentration of interstitial O2 follows Henry’s law at pressures below 13 bar whereas a departure from this model is observed at higher pressures. In particular, O2 concentration saturates abo…

Luminescence Efficiency of Si/SiO 2 Nanoparticles Produced by Laser Ablation

2019

Photoluminescence properties of Si(core)/SiO 2 (shell) nanoparticles produced by pulsed laser ablation in aqueous solution are investigated with the purpose to highlight the microscopic processes that govern the emission brightness and stability. Time resolved spectra evidence that these systems emit a µs decaying band centered around 1.95 eV, that is associated with the radiative recombination of quantum-confined excitons generated in the Si nanocrystalline core. Both the quantum efficiency and the stability of this emission are strongly dependent on the pH level of the solution, that is changed after the laser ablation is performed. They enhance in acid environment because of the H + pass…